Method for removing tetranitromethane from trinitrotoluene



June 21, 1927.

I R. H. G RTNEI; METHOD FOR REMOVING TETRANITROMETHANE FROM TRINITROTOLENE Filed neo. l?, 19,24

AIR CAJRRENT .M COLLECTOR F'OR Wwf @iff/ Patented June 21, 1927.

UNITED STATES vPATENT OFFICE.

RICHARD HANS GRTNER, OF HAMBURG, GERMANY.

METHOD FOR REMOVING TETRANITROMETHANE FROM TRINITROTOLUENE.

Application 1ed December 18, 1924, Serial No. 756,830, and in Germany December 31, 1923.

nitrotoluenes, bi-nitrotoluene and tetranitroy methane.

They can, -it is true, be removed by recrystallization but this is a very tedious and somewhat expensive process, and moreover involves dealing with the mother liquor which is dangerous and unhygienic.

t The format-ion of isomeric trinitrotoluenes and the bi-nitrotoluene can be avoided if nitrotoluene or bi-nitrotoluene free from metanitrotoluene and free, from meta-binitrotoluene is further nitrated. But when nitrating it is imposible to prevent the formation of tetranitromethane which therefore still remains and must be subsequently removed. It has been proposed to blow off the tetranitromethane from the trinitrotoluene by steam or by air but this process requires 'a very large amount ofsteam and also takes considerable time. Moreover the trinitrotoluene, if this process is adopted assumes a dark colour which is not what is wanted.'

The object of the present invention is to discover a method which enables the tetranitromethane to be completely removed from the technical trinitrotoluene without iinpairing the latter and at the same time 0btaining a stable product. sists in the atomization of technical trini trotoluene by a stream of hot air directed from nozzles or similar devices in a manner for atomizing, in addition to the stream of hot air employed for the atomization another stream of hot air is employed to keep the trinitrotoluene drops in a liquid state for a longer period. In the lower part of the chamber the trinitrotoluene will be cooled The method con down by a .stream of cold air and thus solidilied. (lrenerally one treatment will be sufficient to deprive the trinitrotoluene completely of the tetranitromethanc but the process can be repeated if desirable after the trinitrotoluene has been melted again in anyknown manner.

Reference may now be made to'the accompanying drawing in which is illustrated a suitable apparatus for carrying out the method described above.

The trinitrotoluene is melted in a vessel a, from the lower end of which leads the v,pipe b terminating in an atomizing nozzle ein a known manner within the operating tank d. Air heated by a caloriier e is forced by a fan f through the pipe g into the tank d 0pposite the atomizer c, the tetranitromethane being separated from the'trinitrotoluene by this stream of hot air and the trinitrotoluene atomized thereby. The clouds and small particles produced by'the atomizing'nozzle will move downwards within the tank d, and are kept in a liquid state by another stream of hot air admitted through the pipe o from any convenient source. In the lower part d of the tank d a cold stream of air forced into the tank by the fan f cools down the trinitrotoluene. Both the hot air or gases from the top and the cold-.air from below Will be drawn away by the intermediate pipe h, which is preferably not connected directly to the fan f, that communicates directly with the atmosphere through the long vertical pipe z', but through the intermediary of a settling tank lc into the bottom of which the pipe z, projects while the connecting pipe m of the fan f branches ott' from the top of the tank le. This tank serves to absorb the tetranitromethane and also any trinitrotoluene that remains in the gases drawn od by the fan f.

As described above-in the upper part of' the tank d the trinitrotoluene particles are kept for a considerable time in a liquid state by the hot stream of air introduced bythe pipe o. The cold air introduced by the fan f cools the trinitrotoluene to such an extent that it is solidied. The solidified trinitrotoluene. will be collected in the funnel shaped bottom n of the tank d from the exit of which the trinitrotoluene is gathered in a powdered state.

It may be remarked that it is known to dry trinitrotoluene b .causing it to flow in a liquid state over a cated open tray for a lll suiiicient period of time. This process effects drying in a continuous operation, While at the same time exposes only a small quantity at a time to the action of heat and only for a short time. Apart from the fact that it seems very doubtful Whether the trinitrotoluene can be freed by this methodfrom the tetranitromethane it has the disadvantage supposing it to" be used for the purpose which is here in question, that the insanitary tetrantromethane will vescape into the air of the Workroom and that very large mechanical plants Would be required. BothV these drawbacks are absent'from the method proposed by thisV invention.

This method can be' further improved upon by using steam or any other gaseous stream at a suitable pressure for atomizing the trinitrotoluene instead of a stream of hot air. The use of steam has the advantages that the tetranitromethane Will be more easily removed, that the velocity of the stream of steam can be regulated bychanging the pressure and that the constituents evaporated by the steam can be recovered more easily than substances evaporated by air. v

As previously described when hot air is employed for the atomization the atomized trinitrotoluene is kept in a liquid state by another stream of hot air so in a like manner when steam is employed the atomization i Within the upper part of thel chamber is caused by steam and the atomized trinitro toluene is first kept yin a liquid state either by hot air or by steam, and finally is caused to solidify in the lower part of the chamber l by a stream of cold air.

The trinitrotoluene thus produced retains its natural light colour and is free from all foreign constituents that are decomposable or are noxious to the health of the workmen.

Having now particularly described and ascertained the nature of my' said invention and in What manner the same is to be performed, I declare that what I claim is 1. A. method for removing tetranitromethane from commercial trinitrotoluene comprising, atomizing commercial liquid trinitroluene by'means of a nonreactive hot gaseous stream7 subjecting the.clouds thus produced to hot nonreactive gaseous streams until the tetranitromethane is vaporized, then subjecting the trinitrotoluene to cold non-reactive gaseous streams by which the trinitrotoluene is solidified, and then With-l drawing the hot gases from the -presence of the solidified trinitrotoluenel l 2. A method for removing tetranitromethane from commercial trinitrotoluene comprising, atomizing liquid commercial trini- RroHARD HANS-GRTNER. 

